Composition for cleaning and brightening metals



Patented Nov. 24, 1936 UNlTED STATES PATENT orrlcr;-

COMPOSITIONFORCLEANING AND BRIGHTENING METALS Harry B. Rathbun,Waterbury, Conn.

- No Drawing. Application June 10, 1935,

-. 7 Serial No. 25,809

2 Claims. (Cl. 87-5) ing discolorations and stains from the surfaces ofmetal-articles.

One object of this invention is to provide an improved cleaningpreparation of the above na- 19 ture which will produce a durable,bright surface on the metal preparatory to subsequent lacquerng.plating, or drawing operations.

A further object is to provide a preparation of the above nature whichwill produce a durable bright surface on a metal article after it hasbeen annealed and pickled. A further object is to provide a cleaningcomposition of the above nature which may be em 'ployed to facilitatethe galvanic deposition of a 20 Protective metal, such as tin, upon thesurface of non-ferrous metal articles when they are boiled in an aqueoussolution of said composition in the presence of block tin.

A further object isto provide a cleaning and brightening preparationwhich will be simple and inexpensive to manufacture, non-injurious tothe hands of the user, easy to apply, andeflicient in use.

In previous cleaning preparations adapted to be dissolved in water forbrightening metal articles, cream of tartar and acid phosphates havebeen chiefly used as the principal active agents. The former, however,is quite expensive, while the latter is apt to cause the work to becomediscolored if it remains in the solution for any substantial length oftime requiring refinishing. By means of the present invention, acleaning preparation has been provided which avoids the above and otherdisadvantages. 40 The chief active ingredient of the new cleaningpreparation is phthalic anhydride (or acid phthali'c anhydride) CsH4(CO)20, which when dissolved in water reacts to form orthophthalic acid ornaphthalic acid having the formula CBH4 COOH 1L This acid is very weakin hydrogen ionconcentration, and hence exerts only a slight etchingeffect upon the metal to be treated. The preparation also includes aninert electrolyte, such as sodium sulphate (NaaSOQ in order to make thecleaningaction more uniform.

For the purpose of saponifying and emulsifying any oily or fattymaterials which may be present on the surface of the metal articles, thepreparation also includes soap and soap bark,

5 the latter ingredient being an effective foam producer and also knownin the trade as Quillaja, China bark", and Saponaria. (The principalconstituents of soap bark are quillajic acid, quillaja sapotoxin, and.tannin.)

The invention will be further illustrated by the 5 following typicalexample: v

For eachflO pounds of the metal articles to be treated, a solution willbe made up of the following ingredients: 7 v

, 7 Percent 10 Water lbs 2. Phthalic anhydride oz .08 .25 Sodiumsulphate oz .2 .61 Powdered soap "oz-.. .2 .61 Soap bark oz .2 .61 15The metal articles to be cleaned will be placed in a rotating tumblingbarrel, and a sufficient quantity of the aqueous solution will then be 2added to the tumbling barrel until all of the articlesare completelycovered. Or, if desired, the water will first be added to the metalarticles in the'tumbling barreljand the dry ingredients will be laterdissolved therein. 25

It will be understood that the above example isgiven by way ofillustration only, and that the percentages of the ingredients may bevaried to some extent within the spirit of the :vention, 0

' depending upon the amount of work to be treated in' the tumblingbarrels, and the time required to obtain the desired color orbrightness.

One of the desirable features in cleaning preparations for brighteningmetals is that the active 35 ingredient should dissolve only slightly inwater.

The phthalic anhydride preparation according to the present inventionmeets this requirement because it is a material of low solubility, andin use, acts as a reservoir which will slowly give 40 off acid to thesolution as it is used up.

It will be noted that phthalic anhydride has approximately two andone-half times more acid content per unit of weight than cream of tartarand acid phosphates commonly used in such 45 preparations. The presentmarket price of phthalic anhydride is about 10% less than that of creamof tartar, and hence itii vill be seen that phthalic anhydride is farmore economical to use. Moreover, even when a part of the phthalic an--50 hydride is replaced by a neutralsalt, the'preparation will haveapproximately the same etching and cleaning action as the full-strengthcream of tartar or acid phosphate preparations. It is to 5 be understoodthat it is within the scope of the present invention to omit the neutralsalt from the preparation, as the phthalic anhydride alone, mixed withthe soap bark and soap, will also give good results.

It will also be understood that either the soap I bark or soap, or both,may in some cases be omitted from the composition within the scope ofthe invention.-

A further advantage of the cleaning preparation made according to thisinvention is that it is non-poisonous, and will not injure the skin inanyway.

The preparation may also be employed to facilitate the coating byelectrogalvanic-action of metal articles with tin, and to preventdiscoloration of said articles during the process. In operation, sevenor eight alternating layers of block tin and the articles to be coatedwill first be laid in a barrel, preferably of brass-the improvedcleaning preparation in dry form being sprinkled on' the top of eachlayer. Water will, then be added and the contents boiled as long asdesired.

While there have been disclosed in this specification two examples inwhich the invention may secure Letters Patent is:

thereof.

. aoeaose be embodied, it is to be'understood that these examines areshown for the purpose of illustration only, and that the invention isnot to be limited to the specific disclosures but may be modified andembodied in various other 'i'orms without departing irom its spirit; Inshort, the invention includes all the modifications and embodimentscoming within the scope of the following claims. Having thus fullydescribedthe invention, what is claimed as new and for which it isdesired to 10 1. A metal cleaning and brightening composition consistingessentially of 97.92% water, 25% phthalic anhydride, .61 sodiumsulphate,- .6 1%

A soap, and '.61% soap bark,

2. A dry metal cleaning and brightening com-' position consistingessentially of 2 parts by weight of phthalic anhydride, 5 parts ofsodium sulphate. 5 parts of soap, and 5 parts'of soap bark, adapted tobe dissolved in' water for removing deposits 20' a and stains on metals,and preventing tarnishing HARRY B. Ramon.

